Final answer:
Paris is devastated that he cannot marry Juliet.
Step-by-step explanation:
In Act IV, Scene V of Romeo and Juliet, Paris expresses his reaction to Juliet's supposed death with the line, 'Have I thought long to see this morning’s face, and doth it give me such a sight as this?'
This line suggests that Paris is devastated that he cannot marry Juliet. He had been eagerly anticipating their wedding, but now he is faced with the tragic loss of his bride-to-be.
Therefore, option 4: He’s devastated that he cannot marry her, best describes Paris's reaction when he believes that Juliet has died.